Shipping Questions

Recently, I have been trying to sell some ACEO's this past month. I haven't sold ACEO as of yet. Only a few views and maybe a watcher. I want to ship internationally, if possible, to get more sales, as on a TikTok live, they loved the work, but live in Ireland. I have others I made but haven't posted as I haven't had much success on selling them. Before I make more, I want to sell what I already have

There was a period of time I was able to get the .74 cents stamp through eBay for domestic shipping. How will this work internationally? I live in NYC, and I've gotten some of the stamps needed before, as I had to ship something to Candana before, and I still have international stamps.